An electric power tool that includes an electric motor as a drive source is well known. Rotational drive of the electric motor is performed by a controller mounted in the electric power tool. The controller includes a circuit board that can control rotational drive of the electric motor. The circuit board includes a bridge circuit for controlling electric power to the electric motor (for example, refer to Japanese Laid-Open Patent Application No. 2009-214260). Generally, the controller may generate heat by the supplied electric power, and accordingly, a heat radiation member for radiating the heat is provided in the controller.
In the above electric power tool, built-in components may be required to reduce in size and thickness for improving operability. Furthermore, the above-described controller and the circuit board of the controller may be required to reduce in size and thickness as well. Similarly, a heat radiation member may also be required to reduce in size and thickness. However, when the heat radiation member is simply reduced in size or thickness, it may be difficult to perform sufficient heat exchange, which may reduce the heat radiation effect by the heat radiation member.
In view of the above, there is a need to obtain the sufficient heat radiation effect of the controller itself while reducing the size and thickness of the controller including the circuit board and the heat radiation member in the electric power tool.